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bridge: join all-snoopers multicast address
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Next to snooping IGMP/MLD queries RFC4541, section 2.1.1.a) recommends
to snoop multicast router advertisements to detect multicast routers.

Multicast router advertisements are sent to an "all-snoopers"
multicast address. To be able to receive them reliably, we need to
join this group.

Otherwise other snooping switches might refrain from forwarding these
advertisements to us.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Linus Lüssing authored and David S. Miller committed Jan 23, 2019
1 parent a2e2ca3 commit 4effd28
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Showing 3 changed files with 78 additions and 5 deletions.
9 changes: 5 additions & 4 deletions include/uapi/linux/in.h
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Original file line number Diff line number Diff line change
Expand Up @@ -292,10 +292,11 @@ struct sockaddr_in {
#define IN_LOOPBACK(a) ((((long int) (a)) & 0xff000000) == 0x7f000000)

/* Defines for Multicast INADDR */
#define INADDR_UNSPEC_GROUP 0xe0000000U /* 224.0.0.0 */
#define INADDR_ALLHOSTS_GROUP 0xe0000001U /* 224.0.0.1 */
#define INADDR_ALLRTRS_GROUP 0xe0000002U /* 224.0.0.2 */
#define INADDR_MAX_LOCAL_GROUP 0xe00000ffU /* 224.0.0.255 */
#define INADDR_UNSPEC_GROUP 0xe0000000U /* 224.0.0.0 */
#define INADDR_ALLHOSTS_GROUP 0xe0000001U /* 224.0.0.1 */
#define INADDR_ALLRTRS_GROUP 0xe0000002U /* 224.0.0.2 */
#define INADDR_ALLSNOOPERS_GROUP 0xe000006aU /* 224.0.0.106 */
#define INADDR_MAX_LOCAL_GROUP 0xe00000ffU /* 224.0.0.255 */
#endif

/* <asm/byteorder.h> contains the htonl type stuff.. */
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72 changes: 71 additions & 1 deletion net/bridge/br_multicast.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1780,6 +1780,68 @@ void br_multicast_init(struct net_bridge *br)
INIT_HLIST_HEAD(&br->mdb_list);
}

static void br_ip4_multicast_join_snoopers(struct net_bridge *br)
{
struct in_device *in_dev = in_dev_get(br->dev);

if (!in_dev)
return;

ip_mc_inc_group(in_dev, htonl(INADDR_ALLSNOOPERS_GROUP));
in_dev_put(in_dev);
}

#if IS_ENABLED(CONFIG_IPV6)
static void br_ip6_multicast_join_snoopers(struct net_bridge *br)
{
struct in6_addr addr;

ipv6_addr_set(&addr, htonl(0xff020000), 0, 0, htonl(0x6a));
ipv6_dev_mc_inc(br->dev, &addr);
}
#else
static inline void br_ip6_multicast_join_snoopers(struct net_bridge *br)
{
}
#endif

static void br_multicast_join_snoopers(struct net_bridge *br)
{
br_ip4_multicast_join_snoopers(br);
br_ip6_multicast_join_snoopers(br);
}

static void br_ip4_multicast_leave_snoopers(struct net_bridge *br)
{
struct in_device *in_dev = in_dev_get(br->dev);

if (WARN_ON(!in_dev))
return;

ip_mc_dec_group(in_dev, htonl(INADDR_ALLSNOOPERS_GROUP));
in_dev_put(in_dev);
}

#if IS_ENABLED(CONFIG_IPV6)
static void br_ip6_multicast_leave_snoopers(struct net_bridge *br)
{
struct in6_addr addr;

ipv6_addr_set(&addr, htonl(0xff020000), 0, 0, htonl(0x6a));
ipv6_dev_mc_dec(br->dev, &addr);
}
#else
static inline void br_ip6_multicast_leave_snoopers(struct net_bridge *br)
{
}
#endif

static void br_multicast_leave_snoopers(struct net_bridge *br)
{
br_ip4_multicast_leave_snoopers(br);
br_ip6_multicast_leave_snoopers(br);
}

static void __br_multicast_open(struct net_bridge *br,
struct bridge_mcast_own_query *query)
{
Expand All @@ -1793,6 +1855,9 @@ static void __br_multicast_open(struct net_bridge *br,

void br_multicast_open(struct net_bridge *br)
{
if (br_opt_get(br, BROPT_MULTICAST_ENABLED))
br_multicast_join_snoopers(br);

__br_multicast_open(br, &br->ip4_own_query);
#if IS_ENABLED(CONFIG_IPV6)
__br_multicast_open(br, &br->ip6_own_query);
Expand All @@ -1808,6 +1873,9 @@ void br_multicast_stop(struct net_bridge *br)
del_timer_sync(&br->ip6_other_query.timer);
del_timer_sync(&br->ip6_own_query.timer);
#endif

if (br_opt_get(br, BROPT_MULTICAST_ENABLED))
br_multicast_leave_snoopers(br);
}

void br_multicast_dev_del(struct net_bridge *br)
Expand Down Expand Up @@ -1943,8 +2011,10 @@ int br_multicast_toggle(struct net_bridge *br, unsigned long val)

br_mc_disabled_update(br->dev, val);
br_opt_toggle(br, BROPT_MULTICAST_ENABLED, !!val);
if (!br_opt_get(br, BROPT_MULTICAST_ENABLED))
if (!br_opt_get(br, BROPT_MULTICAST_ENABLED)) {
br_multicast_leave_snoopers(br);
goto unlock;
}

if (!netif_running(br->dev))
goto unlock;
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2 changes: 2 additions & 0 deletions net/ipv6/mcast.c
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Original file line number Diff line number Diff line change
Expand Up @@ -940,6 +940,7 @@ int ipv6_dev_mc_inc(struct net_device *dev, const struct in6_addr *addr)
{
return __ipv6_dev_mc_inc(dev, addr, MCAST_EXCLUDE);
}
EXPORT_SYMBOL(ipv6_dev_mc_inc);

/*
* device multicast group del
Expand Down Expand Up @@ -987,6 +988,7 @@ int ipv6_dev_mc_dec(struct net_device *dev, const struct in6_addr *addr)

return err;
}
EXPORT_SYMBOL(ipv6_dev_mc_dec);

/*
* check if the interface/address pair is valid
Expand Down

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